This invention generally relates to the use of chlorous acid for the production of chlorine dioxide in concentrations suitable for use as an oxidizing agent in various industrial processes, more particularly, for removing sulfur dioxide from combustion gases from coal and oil fired furnaces or processes. Other industrial processes where chlorine dioxide may be used as an oxidizing agent include use as a bleaching agent in the paper industry, as a water treatment chemical in the oil recovery industry and as a treatment and disinfecting agent for treating water and/or wastewater.
Methods and/or apparatuses for removing sulfur dioxide from combustion gases have been described in the prior art. Rapson, et al, in U.S. Pat. No. 2,481,241, described a method for removing chlorine from mixtures containing chlorine dioxide and chlorine. Shaheen, in U.S. Pat. No. 3,962,112, described a composition and process for removing sulfur dioxide from combustion gases. Richter, in U.S. Pat. No. 1,685,754, described a method of recovering sulfur dioxide from waste gases. Cheng, in U.S. Pat. No. 4,312,643, described a method of removing sulfur compounds from combustion products exhaust. Fredette, in U.S. Pat. No. 4,393,035, described a method of chlorine dioxide production involving a mixture of hydrochloric and sulfuric acid feed stocks. Fredette, in U.S. Pat. No. 4,393,036 described a method of producing a mixture of sulfuric acid and hydrochloric acid feed involving chlorine dioxide generation therewith. In Bergstrum U.S. Pat. No. 4,508,593, a process for recovering sulfur dioxide was described which involved liberation thereof in the chemical pulping of lignocellulosic materials. Hanisch, et al, in U.S. Pat. No. 376,883, described a process of obtaining sulfurous acid from furnace gases or simularly composed gaseous mixtures.
However, none of the prior art cited above discloses the unique method of preparing chlorine dioxide from chlorous acid for use for the removal of sulfur dioxide from combustion gases as does the present invention.